Over the past forty years, businesses have sought to maximize efficiency by using various devices to automate data entry. In the important area of inventory management, in particular, the indicia-reading device (e.g., barcode reader or barcode scanner) has greatly reduced the time and errors inherent to manual data entry.
Indicia-reading devices are often employed to decode barcodes. A barcode is a machine-readable representation of information in graphic format. Traditionally, a barcode is a series of parallel bars and spaces of varying widths (e.g., a linear barcode or 1D barcode). More recently, there has been an increase in the use of alternatives to the linear barcode. For example, matrix codes (e.g., 2D barcodes or QR Code) and Optical Character Recognition (i.e., OCR) have enjoyed increasing popularity as the technology advances. As used herein, the terms barcode, indicia, and code-symbol are intended in their broadest sense to include linear barcodes, matrix barcodes, and OCR-enabled labels.
Indicia readers (e.g., barcode readers) tend to fall into one of three categories: wand readers, laser-scan-engine readers, and image-sensor readers. Wand readers generally include a single light source and single photodetector housed in a pen shaped housing. A user drags the wand reader across a barcode and a signal is generated representative of the bar-space pattern of the barcode.
Laser-scan-engine readers typically include a laser diode for generating a light beam and a moving mirror for sweeping the light beam across a code symbol. A signal from the reflected light corresponds to the barcode.
Image-sensor readers include a multi-element image sensor, such as a complementary-metal-oxide semiconductor (i.e., CMOS) image sensor, for generating an electronic signal representing an image formed on the image sensor. These readers include an imaging optic for focusing an image onto the image sensor. Image-sensor readers capture a digital picture of a target (e.g., barcode) and use software algorithms running on a processor to find and decode the symbol into useful information. Image-sensor readers offer more features than other types of readers. These features result from the versatility of the image processing algorithms. The limits of these algorithms are based on the processing resources available from the device.
Virtually all thin-profile, hand-held, mobile computing devices now have integrated cameras. As a result, applications capable of utilizing the integrated camera as an image sensor for indicia reading have been developed. While these applications perform reasonably well for the casual user, they lack the features and functions present in a dedicated image-sensor reader. Illumination, aiming, stabilization, and focusing could all suffer when using the integrated camera for indicia reading.
Carrying a single mobile computing device is desirable to most users. These users will be reluctant to trade their mobile computing device (i.e., MCD) for a dedicated indicia-reading device. Fortunately, an indicia-reading module, with all of the features of a dedicated indicia-reading device, can be integrated with an MCD without being bulky. Such a module must be small to allow for seamless integration with the MCD. The module must integrate with the MCD in such a way as to allow for imaging. These integration requirements place severe limitations on the design of the indicia-reading module. Unique design approaches and construction methods must be combined to facilitate the consequences of the integration within the body of a slim MCD.
The image sensor used in an indicia-reading module is especially sensitive to temperature, and its performance quickly degrades as the module temperature rises. High temperatures within an MCD are unavoidable. Thermal management, therefore, is an important design consideration for an indicia-reading module that is to be integrated within an MCD. The indicia-reading module must dissipate heat in spite of its small volume and surface area and do so in a space where heat transfer through convection is greatly limited. A need, therefore, exists for a conductive module heat-dissipation structure to insure module temperatures for proper operation.